(a) Field of the Invention
The present invention relates to a control system of a hybrid vehicle and a control method, more particularly, to a control system which can improve fuel efficiency and secure available power of a driving motor in a vehicle that is running in a high elevated area, without a hardware change, and a method thereof.
(b) Description of the Related Art
A hybrid vehicle refers to a vehicle with an internal combustion engine and an electric vehicle, and which uses two or more power sources, for example, power of an engine and power of a battery.
When such a hybrid vehicle runs in a high elevated area, the density of the air sucked into the engine is low, so the power from the engine decreases. It is known that as an altitude increases by 1000 m, the power from an engine generally decreases by 10%.
Accordingly, since the power from an engine decreases in a high elevated area in comparison to a flatland, for the same necessary torque, the decreased power of the engine is compensated by operating a driving motor.
However, when a driving motor continuously operates, the SOC (State Of Charge) of a battery is reduced, and when the power from an engine is used to charge the battery, it takes more time to charge the battery, as compared with when a vehicle runs on the ground at sea level.
Further, as the battery takes more time to charge, the SOC of the battery is decreased by continuous operation of the driving motor, such that the roadability of the vehicle running in a high elevated area decreases. In particular, the term “roadability” refers to the ability of the hybrid vehicle to maintain a steady, balanced, and comfortable ride under a variety of road conditions.
In order to solve those problems in the related art, a method of changing the final gear ratio was used, but there is a need for a hardware change to change the final gear ratio, resulting in an increase in manufacturing cost of a vehicle.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.